The present invention relates to a method and apparatus for detecting a fluid; use thereof for detecting the level of fluid in a container; and use thereof for monitoring a leak of fluid from a body containing said fluid, in particular a leak of body fluid from a human or an animal.
The present invention further relates to a method and apparatus for detecting a temperature.
The present invention still further relates to a sensing device for sensing an external parameter, in particular a fluid or a temperature.
1. The Technical Field
Generally detection of a fluid, e.g. for detecting the level of a fluid in a container or for detecting a leak of fluid from a body such as a container or a human or animal body containing said fluid comprises production of a sensor signal of the fluid and detection of the produced sensor signal by appropriate detection electronics.
In applications of e.g. detecting levels or leaks of stationary oil containers, or detecting leak of body fluids from patients or elderly confined to a bed, the sensor of the fluid and the detection electronics are typically interconnected by electrically conducting connectors e.g. wires or cables. However, such connections can be sensitive to damage and for patients or elderly confined to a bed they can be very inconvenient and put severe constrains on their movability.
Particularly for patients or elderly who are able to walk around, such electrical connections cannot be used without restricting their movability.
Since lack of movability of patients and elderly requires an increased level of monitoring of e.g. wounds and urinary and faecal incontinence by personnel, such a monitoring often being considered inconvenient and cumbersome, electrical connections of monitoring devices implicitly contribute to bad sanitary conditions for patients and elderly and contaminated environments of wound healing sections, incontinence sections and the like of hospitals and nursery homes.
A similar situation holds for monitoring the temperature of patients and elderly.
Wireless connection based on suitable receiver/-transmitter electronics at the sensor and detection electronics can be contemplated. However, in order to function, such electronics requires a portable power supply such as a voltage battery. This is impractical because of the necessary exchange or recharge of discharged batteries.
Consequently there is a need for wireless connection of fluid sensor, or temperature sensor, respectively, and detection electronics which do not require portable power supply; as well as sensors suited for sensing exposure of an external parameter, in particular fluid or a temperature without requiring external power supply.
2. Prior Art Disclosures
International Application No. PCT/NL/00083 discloses an assembly for detecting and signalising wetness of a diaper; said assembly comprising an electronic device mounted in a housing to be applied on a diaper and directly connected to connectors on a sensor strip adhered to the inside or outside of said diaper for detecting presence of wetness near said conductors.
U.S. Pat. No. 4,646,066 discloses an indicator device and method of measuring incremental environmental exposure of an environmental parameter; said method comprising measuring responses of a target to an electromagnetic interrogation signal; said target. including a tuned circuit and an element that is sensitive to environmental exposure, especially exposure to specified fluids e.g. liquids and water vapour, influencing the electronic or ionic conductivity. There is no teaching of parameter influences including the capacitance of the tuned circuit, nor of a measuring method based on changes of transmission of electromagnetic energy of oscillators transmitting electromagnetic energy to the tuned circuits.
EP 0 715 152 discloses a sensing device for sensing the presence or absence of an article, e.g. a material, a liquid, a powder, and the human body; said device comprising an oscillator for generating a high frequency signal; a sensor including a resonance circuit for receiving the high frequency signal from the oscillator and a detector for producing a signal relating to a variation of an impedance change of the sensor; said sensor and detector being coupled through a cable.
GB 2 113 835 discloses a sensor for detecting quantities such as position, force, pressure, liquid level, flow, temperature, voltage, current, and magnetic field; said sensor comprising opto-electric means for converting optical energy into electric energy and vice versa and at least one electric resonant circuit and means arranged to influence a characteristic of the resonant circuit by the quantity to be detected.
U.S. Pat. No. 5,570,082 discloses a device for detecting wetness in diapers for the purpose of calling the attention of the caretaker. The device is a combination of an antenna, a non-linear element and two parallel electrodes, the two electrodes being enbedded in the diaper in an area likely to experience wetness and being adapted to provide a strong coupling between the antenna and the non-linear device when subjected to wetness thereby reducing the resistance between the electrodes. This device does not include a resonant circuit.
It is an object of the present invention to provide a method and apparatus for detecting a fluid without using an electrical connection between a sensor of the fluid and an electronic detection system therefore and without requiring a portable power supply for the fluid sensor.
It is another object of the present invention to provide a method and apparatus for detecting the level of a fluid in a container, in particular the level of a human body fluid collected in a container; or for detecting the level of an infusion liquid in a container, in particular the level of an infusion liquid in a plastic bag, e.g. of soft plastic that collapses during emptying thereof.
It is another object of the present invention to provide a method and apparatus for detecting a body fluid from a human or animal body, in particular a leak of body fluid from a human suffering from e.g. urinary and/or faecal incontinence, a human or animal undergoing surgery requiring a drain of body fluid, or a human or animal having e.g. a bleeding wound.
It is another object of the present invention to provide a method and apparatus for detecting a temperature.
It is another object of the present invention to provide sensors for such methods and apparatus
Further objects will be apparent from the description,
In an aspect, the present invention relates to a method and an apparatus for detection of a fluid, and use thereof.
xe2x80x9cMethod of Detecting a Fluidxe2x80x9d
In an aspect according to the invention these objects are achieved by providing a method of detecting a fluid as claimed in claim 1; said method comprising providing one or more oscillators transmitting electromagnetic energy; providing one or more resonant circuits receiving electromagnetic energy from the oscillators; bringing the fluid and the one or more resonant circuits into contact with each other so that the receptions of electromagnetic energy of the resonant circuits are changed; and detecting changes of the transmissions of electromagnetic energy of the oscillators by changes in one or more characteristics thereof upon the changes in the receptions of the electromagnetic energy of the resonant circuits, whereby receiver circuits for receiving and detecting responses of the resonant circuits can be avoided.
xe2x80x9cApparatus for Detecting a Fluidxe2x80x9d
In another aspect according to the invention these object are further achieved by providing an apparatus as claimed claim 6; said apparatus comprising one or more oscillators for transmitting electro-magnetic energy; one or more resonant circuits for receiving electromagnetic energy from said oscillators; and one or more detectors for detecting changes in one or more characteristics of the one or more oscillators upon changes in characteristics of the resonant circuits by contact thereof with the fluid, whereby a simplified apparatus is obtained which avoids receiver circuits for receiving and detecting responses of the resonant circuits.
According to the invention it surprisingly turns out that electrically conducting connectors between the sensor of the fluid and the detection electronics, and battery power supply of the sensor, and receiver circuits for receiving and detecting responses of resonant circuits of the sensors can be avoided.
This provides a number of advantages e.g. that the sensor of the fluid can be separated from the detection electronics for detecting changes in the sensor. This is particularly advantageous when monitoring bodies containing fluid wherein the sensor and the detection electronics used cannot be connected permanently by electrically conductions connectors, or when they can only be connected by such connectors with great difficulties or inconveniences. Also, the oscillators and detection electronics can be simplified.
xe2x80x9cUses of the Method and Apparatus for Detecting a Fluidxe2x80x9d
Accordingly, in still another aspect according to the invention there is provided uses of the method or the apparatus as claimed for detection of fluid level in one or more containers, in particular incontinence containers, specifically diapers; and use for detecting whether a container containing a fluid has been emptied for the fluid in particular emptying of an infusion containing use for monitoring leak of fluid from a container, or a human or animal body, in particular from a human suffering from urinary and/or faecal incontinence; whereby the health care personnel can monitor the hygienic condition of e.g. a diaper. When a body leak has been detected proper care of e.g. changing the diaper can then be taken.
Another aspect of the invention relates to a method and an apparatus for detection of a temperature, or a temperature difference, and use thereof.
xe2x80x9cMethod of detecting a temperaturexe2x80x9d
In an aspect according to the invention these objects are achieved by providing a method of detecting a temperature; said method comprising providing one or more oscillators transmitting electromagnetic energy; providing one or more resonant circuits receiving electromagnetic energy from the oscillators; exposing the the one or more resonant circuits to the temperature to be detected so that the receptions of electromagnetic energy of the resonant circuits are changed; and detecting changes of the transmissions of electromagnetic energy of the oscillators by changes in one or more characteristics thereof upon the changes in the receptions of the electromagnetic energy of the resonant circuits, whereby receiver circuits for receiving and detecting responses of the resonant circuits can be avoided.
xe2x80x9cApparatus for Detecting a Temperaturexe2x80x9d
In another aspect according to the invention these object are further achieved by providing an apparatus; said apparatus comprising one or more oscillators for transmitting electromagnetic energy; one or more resonant circuits for receiving electromagnetic energy from said oscillators; and one or more detectors for detecting changes in one or more characteristics of the one or more oscillators upon changes in characteristics of the resonant circuits by exposure thereof to a temperature, whereby a simplified apparatus is obtained which avoids receiver circuits for receiving and detecting responses of the resonant circuits.
According to the invention it surprisingly turns out that electrically conducting connectors between the sensor of the temperature and the detection electronics, and battery power supply of the sensor, and receiver circuits for receiving and detecting responses of resonant circuits of the,sensors can be avoided.
This provides a number of advantages e.g. that the sensor of the temperature can be separated from the detect on electronics for detecting changes in the sensor. This is particularly advantageous when monitoring bodies for a temperature wherein the sensor and the detection electronics used cannot be connected permanently by electrically conductions connectors, or when they can only be connected by such connectors with great difficulties or inconveniences. Also, the oscillators and detection electronics can be simplified.
xe2x80x9cUses of the Method and Apparatus for Temperature Measurementxe2x80x9d
In addition to the use of the fluid detection method and apparatus described above, the present invention additionally provide the use of the method and apparatus as claimed for detection of a temperature.
Temperature sensors comprising temperature sensitive resonant circuits may be designed to change their impedances at predetermined temperatures, typically in the range 35-42xc2x0 C., preferably 36-40xc2x0 C., most preferred 36-38xc2x0 C., particularly about 37xc2x0 C.
In addition to monitor patients or elderly for leak of body fluid, or supply of fluid to the body, their temperature can be monitored.
xe2x80x9cSensing Devices of External Parametersxe2x80x9d
Still another aspect of the present invention relates to sensors usable for such methods and apparatus in sensing external parameters, more specifically it relates to sensing devices comprising resonant circuits which are responsive, to parameters that are able to influence the impedance thereof, e.g. responsive to a fluid or a temperature.
According to an aspect of the invention, there is provided a sensing device said device comprising a substrate having a back side and a front side, and at least one electrical conducting means, comprising an inductance positioned on or embedded in said back side, front side, or both, of the substrate; said substrate further having at least two parts in a mutual overlaying relationship, so that said conducting means together with at least a part of the substrate provide a capacitance; said inductance and capacitance being electrically connected to form a resonant circuit; and said conducting means being exposed to the external parameter to affect a parameter of said resonant circuit, whereby there is provided a resonant circuit which is easy to manufacture, e.g. by mass manufacturing using continuous substrate coating techniques.
In a preferred embodiment, the two folded sides of the substrate are rotatable around the folding axis, whereby it is obtained that the capacitance formed therebetween can be varied. This embodiment is particular useful when the sensing device is tagged to two sides of a container which sides can get closer or further apart depending on the container having a content, e g. fluid or not. An example being a urine collection bag having a sensing device tagged to the edge thereof, the sides of the bag getting further apart as the bag is being filled.
In a preferred embodiment, the sensing device comprises accession means for a fluid to affect the impedance of the resonant circuit thereby making the sensor particularly suited for detecting a fluid.
In another preferred embodiment, the sensing device comprises a temperature sensitive means thereby allowing remote and wireless monitoring of the temperature of e.g. a patient or an elderly.
xe2x80x9cArticles Comprising the Sensing Devicexe2x80x9d
In another aspect of the present invention there is provided an article comprising the sensing device including a transmitter/receiver combination.
Preferred articles include, but are not limited to, articles for containing or for taking up fluid or for delivering fluid; and articles for measuring temperature; such container e.g. being monitored for being filled or being emptied.
In a preferred embodiment, the article consists of an hygienic article for healthy development and maintenance of health.
In a particularly preferred embodiment, the article consists of an absorbent or a bandage in form of a wrap or a trapping used to protect, cover or immobilise an injured or diseased part of a human or an animal, or used during surgery.
In a particularly preferred embodiment, the article consists of an absorbent for urine or facea, in particular diaper.
xe2x80x9cUse of Articles Comprising the Sensing Devicexe2x80x9d
Articles comprising a sensing device according to the present invention are preferably used in a method of monitoring hygienic conditions of one or more patients said method comprising applying one or more hygienic articles according to the invention to one or more patients, each article having a sensing device with a resonant circuit that differ from each other; and transmitting electromagnetic energy to said resonant circuits.
In an embodiment, the method further comprises monitoring at least one response of said resonant circuits, thereby allowing the prior art techniques of interrogating the resonant circuit to be used.
In a preferred embodiment, the method further comprises monitoring changes of the transmission of electromagnetic energy of one or more oscillators transmitting electromagnetic energy to said resonant circuits, thereby obtaining the advantages of the method according to .the present invention.
Further advantages will be apparent from the description.
In its broadest aspect, the sensing device according to the present invention does not necessarily depend on the method of detecting changes of one or more characteristics of the resonant circuit, i.e. for example by detecting the change of the transmission of electromagnetic energy of the oscillators according to the invention, or by detecting a response of the resonant circuit according to prior art methods. However, the specific resonant circuit used typically depends on the parameter to be detected, e.g. fluid or temperature.
Known methods include those referenced in U.S. Pat. No. 4,646,066, e.g. U.S. Pat. No. 4,321,586.
According to the aspect of the invention relating to detecting a fluid, a resonant circuit has one or more characteristics which change by contact between the resonant circuit and a fluid.
According to the other aspect of the invention relating to detecting a temperature or a temperature difference, a resonant circuit has one or more characteristics which change by exposing the resonant circuit to different temperatures.
In a preferred embodiment of both aspects, the characteristics comprises resistance, capacity, inductance, or any derivative thereof.
By contact of the resonant circuit with the fluid, or by exposing the resonant circuit to different temperatures, one or more of the characteristics resistance R, capacitance C and inductance L, or any derivative thereof, e.g. the resonance frequency xcfx89o=(LC)xe2x88x9212, or higher harmonics thereof, or the quality factor Q=xcfx89L/R, e.g. at resonance xcfx89=xcfx89o,change.
When one or more of the characteristics change, the ability of the resonant circuit to receive electromagnetic energy changes. This can be detected by detecting changes in one or more characteristics of one or more oscillators transmitting electromagnetic energy to said resonant circuit.
Generally, sensing devices can be manufactured in any suitable way that allow the external parameters to affect the impedance of the respective resonant circuits.
In the particular aspect of the invention relating to detecting a fluid, resonant circuits can be prepared in any suitable way that ensures the penetration of fluid into the resonant circuit to such an extent that one or more of its characteristics are changed.
In the particular aspect of the method of detecting a fluid, the. change of characteristics of the resonant circuit causes a detectable change in one or more of the characteristics of the one or more oscillators.
In a preferred embodiment, the resonant circuit consists of a coil having separated windings which can receive the fluid and short cut the circuit.
The windings can be of any suitable material. In a preferred embodiment, the windings are made of an electrically conducting material selected from the group consisting of metals such as aluminium, copper, tin; an electrically conducting polymer such as polyaniline; and an electrically conducting polymer blend such as poly(p-phenylene vinylene), polyacrylamide, polyaniline and polyethylene, or combinations of these.
Specifically useful electric conducting polymers include a flexible, crease resistant, one component, carbon filled ink and coating sold by Emerson and Cuming Speciality Polymers under the trademark Amicon C 932-74. Another useful electric conducting polymer is a higly flexible, crease resistant, one component, silver filled, ink and coating sold by Wacker Chemikemi under the trademark Elastosil N 189. Both products are environmentally acceptable.
In the particularly aspect of detecting temperature changes, the resonant circuits can be prepared in any suitable way that ensures the influence of different temperatures to affect the impedance of the resonant circuit to such an extent that one or more of its characteristics are changed.
In the particular aspect of the method of detecting a temperature change, the change of the characteristics of the resonant circuit causes a detectable change in one or more of the characteristics of the one or more oscillators.
In a preferred embodiment, the resonant circuit consists of a coil having separated windings of which the resistance, inductance, or both, are sensitive to temperature.
The windings can be of any suitable material. In a preferred embodiment, the windings are made of a temperature sensitive, electrically conducting material.
In another preferred embodiment, the coil has to parts serially connected through a temperature sensitive resistance.
The fluid sensing device can be placed in. any suitable position to detect the desired fluid. In preferred embodiments, the fluid sensing device is contained in or attached onto a container; or it is embedded in a diaper; or it is embedded in a carrier with an adhesive, such as a sticker, to be attached on a desired location, e.g. onto said container or diaper.
Several resonant circuits can be positioned in one location to encode for given patterns of frequencies, e.g. several small resonant circuits of e.g. different frequencies placed in a diaper can provide a unique identification of e.g. individual patients or elderly being monitored in a hospital or a nursing home.
According to the invention an oscillator operates in functional proximity of a resonant circuit.
In the present context the expression xe2x80x9cfunctional proximity of a resonant circuitxe2x80x9d is intended to mean that an oscillator in one location radiates electromagnetic energy, e.g. in form of radiowaves or microwaves, which can be fully or partly transferred to a resonant circuit in another location.
Generally, any suitable oscillator can be used, i.e. an oscillator which is able to produce electromagnetic oscillations and to emit electromagnetic energy e.g. in form of radiowaves or microwaves which is fully or partly received by the resonant circuit.
It should be understood that more than one oscillator can operate in functional proximity of said resonant circuits e.g. if more oscillators operates at different frequency ranges, and if changes in different characteristics of the resonant circuit are to be detected.
Generally, an oscillator comprises an generator which generates a high frequency signal of radiant energy e.g. an ac current or voltage, or an impulse, of a frequency around that of the resonant circuit. Generators can be any suitable generator known in the art, e.g. radio frequency signal. generators.
In a preferred embodiment, the oscillator comprises a generator generating a signal of electromagnetic energy of a frequency around that of the resonant circuit.
An oscillator comprises one or more inductors. The inductors can be internal or external to a cabinet housing the oscillator. Preferably there is one or more inductors for each different bands of operation for each resonant circuit. Preferably more inductors can be interchanged either manually or automatically. The inductors can be of any suitable form. In a preferred embodiment the inductors are external inductors in form coils.
Functional proximity between the oscillators and the resonant circuits can be achieved in any suitable way. In a preferred embodiment, the inductors are external inductors in form of coils which surrounds the resonant circuit. In a particularly preferred embodiment, the coils are embedded in a bed for monitoring leak of body fluids of a human.
In another preferred embodiment, the oscillators comprises one or more antennas whereby the direction of the electromagnetic, radiation, e.g. radio waves, can be more accurately defined. An antenna can be any suitable antenna known in the art, e.g. a dipole. In a preferred embodiment, the antenna comprises a radiator element, transmission lines, and optional transformers, coupled to the inductor, or constituting a part of the inductor.
The apparatus further comprises one or more detectors for detecting one or more changes in one or more characteristics of said oscillators upon changes in the characteristics of one or more resonant circuits.
The characteristics of the oscillators comprise any suitable characteristic.
In a preferred embodiment the characteristics of the oscillator comprise current, voltage, or a derivative thereof such as power, whereby one or more characteristics, or derivatives thereof, of the resonant circuit are detected, e.g. change in frequency, particularly the resonance frequency; change in quality factor; and wholly or partial suppression or restoration of any of these.
In a preferred embodiment one or more of the detectors detect an increase or a decrease of energy loss of one or more of the oscillators.
Further, preferred uses appear from the following detailed description.